A translation of the posting on the DRG forum.

Quote Originally Posted by inventor
For our machines , it's not that difficult to buy ready to use parts. RX/TX, chargers and batteries, even esc's are readely available, and the information is floating around to be picked up at leasure.
But drives in between beetles and heavy duty feather are rare. Most of the time, people repurpose the batterydrill equivalents for the 6 kg machines.
In Germany, several roboteers are using the way smaller small batteryscrewdrivers to power their raptors and even feathers. It takes a lot of customisation tough.
Body and end shaft are not up to the task. The 3 stage gearbox is also a point as the end speed with a normal size wheel will be glacial.

A ruggedized 2 stage version is tested.

Specs gearbox:
size excl. motor: 65x40x30mm
size incl. motor: +-103x40x30mm (depends on motor used)
weight excl. motor: 140gr
weight incl. motor: +-250gr (depends on motor used)
gearratio: 1:20
mounting pattern motor: 4xM3 16mm and 19mm
Mounting pattern gearbox: 8x M4
End shaft: D12 L30 keyway 4mm.
End shaft bearings: 2x61901-2Z






The gearboxes, with the 2 different motor mounting pattern options can fit most 380 size motors but also a lot of 28mm diameter brushless motors as this one.

Unfortunatly, the uncompromizing upgrades make it £40 each if the basic batch is 10 pairs.

Dennis Martens, Metal Skull Robotics
PS, Inventor is the guy who gave us the MSR 12-54 and 12-72 Speed 900 drivetrains. I just made the most of those on his designs.